The video format used to store digital video on commercial DVD discs.

DVD-Video is a consumer video format used to store digital video on DVD discs. DVD-Video was the dominant consumer home video format in Asia, North America, Europe, and Australia in the 2000s until it was supplanted by the high-definition Blu-ray Disc. Discs using the DVD-Video specification require a DVD drive and a MPEG-2 decoder (e. g., a DVD player, or a computer DVD drive with a software DVD player). Commercial DVD movies are encoded using a combination MPEG-2 compressed video and audio of varying formats (often multi-channel formats as described below). Typically, the data rate for DVD movies ranges from 3 Mbit/s to 9.5 Mbit/s, and the bit rate is usually adaptive. DVD-Video was first available in Japan on November 1, 1996 (with major releases beginning December 20, 1996), followed by a release on March 24, 1997, in the United States - to line up with the 69th Academy Awards that same day.

The DVD-Video specification was created by DVD Forum and can be obtained from DVD Format/Logo Licensing Corporation for a fee of $5,000. The specification is not publicly available and every subscriber must sign a non-disclosure agreement. Certain information in the DVD Book is proprietary and confidential.

Video data

To record digital video, DVD-Video uses either H.262/MPEG-2 Part 2 compression at up to 9.8 Mbit/s (9,800 kbit/s) or MPEG-1 Part 2 compression at up to 1.856 Mbit/s (1,856 kbit/s). DVD-Video supports video with a bit depth of 8 bits per color YCbCr with 4:2:0 chroma subsampling.

The following formats are allowed for H.262/MPEG-2 Part 2 video:

At a display rate of 25 frames per second, interlaced (commonly used in regions with 50 Hz image scanning frequency):

  • 720 × 576 pixels (same resolution as D-1)
  • 704 × 576 pixels
  • 352 × 576 pixels (same as the China Video Disc standard)
  • 352 × 288 pixels

At a display rate of 29.97 frames per second, interlaced (commonly used in regions with 60 Hz image scanning frequency):

  • 720 × 480 pixels (same resolution as D-1).
  • 704 × 480 pixels
  • 352 × 480 pixels (same as the China Video Disc standard).
  • 352 × 240 pixels

The following formats are allowed for MPEG-1 video:

  • 352 × 288 pixels at 25 frame/s, progressive (Same as the VCD Standard)
  • 352 × 240 pixels at 29.97 frame/s, progressive (Same as the VCD Standard)

Video with 4:3 frame aspect ratio is supported in all video modes. Widescreen video is supported only in D-1 resolutions.

The MPEG-1 Part 2 format does not support interlaced video. The H.262/MPEG-2 Part 2 format supports both interlaced and progressive-scan content. Content with a frame rate different from one of the rates shown above can be encoded to H.262/MPEG-2 Part 2 by using pulldown. This is most commonly used to encode 23.976 frame/s content for playback at 29.97 frame/s. Pulldown can be implemented directly while the disc is mastered, by actually encoding the data on the disc at 29.97 frames/s; however, this practice is uncommon for most commercial film releases, which provide content optimized for display on progressive-scan television sets.

Alternately, the content can be encoded on the disc itself at one of several alternate frame rates, and use flags that identify scanning type, field order and field repeating pattern. Such flags can be added in video stream by the H.262/MPEG-2 Part 2 encoder. A DVD player uses these flags to convert progressive content into interlaced video in real-time during playback, producing a signal suitable for interlaced TV sets. These flags also allow reproducing progressive content at their original, non-interlaced format when used with compatible DVD players and progressive-scan television sets.

Audio data

The audio data on a DVD movie can be PCM, DTS, MPEG-1 Audio Layer II (MP2), or Dolby Digital (AC-3) format. In countries using the PAL system standard DVD-Video releases must contain at least one audio track using the PCM, MP2, or AC-3 format, and all standard PAL players must support all three of these formats. A similar standard exists in countries using the NTSC system, though with no requirement mandating the use of or support for the MP2 format. DTS audio is optional for all players, as DTS was not part of the initial draft standard and was added later; thus, many early players are unable to play DTS audio tracks. Only PCM and DTS support 96 kHz sampling rate. Because PCM, being uncompressed, requires a lot of bandwidth and DTS is not universally supported by players, AC-3 is the most common digital audio format for DVDs, and 96 kHz is rare on a DVD. The official allowed formats for the audio tracks on a DVD-Video are:

PCM: 48 kHz or 96 kHz sampling rate, 16 bit or 24 bit Linear PCM, 2 to 6 channels, up to 6,144 kbit/s; N. B. 16-bit 48 kHz 8 channel PCM is allowed by the DVD-Video specification but is not well-supported by authoring applications or players;

AC-3: 48 kHz sampling rate, 1 to 5.1 (6) channels, up to 448 kbit/s;

DTS: 48 kHz or 96 kHz sampling rate; channel layouts = 2.0, 2.1, 5.0, 5.1, 6.1; bitrates for 2.0 and 2.1 = 377.25 and 503.25 kbit/s, bitrates for 5.x and 6.1 = 754.5 and 1509.75 kbit/s;

MP2: 48 kHz sampling rate, 1 to 7.1 channels, up to 912 kbit/s.

DVDs can contain more than one channel of audio to go together with the video content, supporting a maximum of eight simultaneous audio tracks per video. This is most commonly used for different audio formats—DTS 5.1, AC-3 2.0, etc.—as well as for commentary and audio tracks in different languages.

Data rate

DVD-Video discs have a raw bitrate of 11.08 Mbit/s, with a 1.0 Mbit/s overhead, leaving a payload bitrate of 10.08 Mbit/s. Of this, up to 3.36 Mbit/s can be used for subtitles, a maximum of 10.08 Mbit/s can be split amongst audio and video, and a maximum of 9.80 Mbit/s can be used for video alone. In the case of multiple angles the data is stored interleaved, and so there is a bitrate penalty leading to a max bitrate of 8 Mbit/s per angle to compensate for additional seek time. This limit is not cumulative, so each additional angle can still have up to 8 Mbit/s of bitrate available.

Professionally encoded videos average a bitrate of 4–5 Mbit/s with a maximum of 7–8 Mbit/s in high-action scenes. Encoding at less than the max bitrate (like this) is typically done to allow greater compatibility among players, and to help prevent buffer underruns in the case of dirty or scratched discs

Aiming to improve picture quality over standard editions, Columbia TriStar Home Entertainment offered "Superbit"—a premium line of DVD-Video titles having average bitrates closer to 6 Mbit/s. Audio quality was also improved by the mandatory inclusion of both Dolby Digital and DTS 5.1 surround audio tracks. Multiple languages, angles, and extra audio tracks were eliminated to free up more space for the main title and thereby to ensure the highest data rate possible. In January 2007 the Superbit line was discontinued.
Other features

Some DVD hardware or software players may play discs whose MPEG files do not conform to the above standards; commonly this is used to support discs authored with formats such as VCD and SVCD. While VCD and CVD video is supported by the DVD standard, neither SVCD video nor VCD, CVD, or SVCD audio is compatible with the DVD standard.

Some hardware players will also play DVD-ROMs or CD-ROMs containing "raw" MPEG video files; these are "unauthored" and lack the file and header structure that defines DVD-Video. Standard DVD-Video files contain extra information (such as the number of video tracks, chapters, and links to extra features) that DVD players use to navigate the disc.

The maximum chapters allowed per title is 99 and the maximum titles allowed per DVD is 99.

Adapted from content published on wikipedia.org
Last modified on December 2, 2020, 9:03 pm
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